This invention relates to a coordinates detector for detecting a designation position in a coordinates plane.
A coordinates detector utilizing light, such as an infrared ray, is conventionally known which is adapted to detect the presence or absence of input position data depending upon whether direct light is blocked which light passes through a portion corresponding to a desired position in a coordinate plane. That is, a plurality of pairs of light emitting and receiving elements are arranged such that pairs of light emitting and receiving elements in an X direction are located in parallel and in a Y direction are located in parallel on the orthogonal coordinates (X, Y) plane. The pairs of X and Y direction light transmitting and receiving elements are sequentially scanned to obtain a detection output and, when an optical path between a pair of light transmitting and receiving elements is shut off by a position designation, the corresponding X and Y direction position data can be obtained due to the interruption of light on the optical path mentioned.
With N and .DELTA.t representing a sum of pairs of X and Y direction light emitting and receiving elements and the time required for one pair of light transmitting and receiving elements to be scanned, the time T required for all pairs of X and Y direction light emitting and receiving elements to be scanned is expressed as follows: EQU T=N.times..DELTA.t (1)
Therefore, if the number of light emitting and receiving elements is increased in order to perform a position detection operation over a wider range or an exact position detection operation, an extension in time is required for performing a scanning operation, resulting in a delay in the position detection and a decrease in the response characteristic.